I was driving through the Rocky Mountains thinking about nothing much except whether to have another mint when something remarkable happened. A disembodied voice said, "Let's take the next left to Athabasca Falls…" And I did exactly as I was told. Never mind the fact that the voice was coming from a box stuck to my windscreen.

I took the turn, trotted off to see some waterfalls, precisely as commanded. And when I came back The Voice told me to drive on, adding, "Hope you didn't get too wet!"

Welcome to the intriguing world of GyPSy, a device that's changing the face of holiday drives in Canada, and spreading to other parts of the world. Using the same direction-finding technology that powers satnavs, this gizmo senses which tourist route you have chosen and not only gives directions to your ultimate destination, it also comments on sights you pass, offers historical background and local stories, suggests where to take photographs, and proposes side trips – from which it will guide you back to the main road.

I had picked it up at Calgary airport from a woman at the tourist office who explained how to link it to my hire-car radio – and as I nosed into the airport traffic, The Voice spoke to me with a sense of command that was to dominate the next 500 miles. In a drawling, down-home Canadian accent that changed personality and even sex during the following days, it gave me alternatives. Did I want to drive to Calgary? Turn right. The Rockies? Keep going…

As unseen satellites monitored my progress, The Voice then began a periodic commentary on my journey, offering stories that were at times accurate to within yards. During a tale about the history of horse-riding on these prairies, for instance, I found myself driving past fields full of the beasts. When I got my first sight of the looming Rockies, I heard, "Those mountains'll be with us for the next few hundred kilometres!" On I motored.

I had decided on a four-day journey from Calgary to the cheery Rockies town of Banff, then north along the lonesome Icefields Parkway to Lake Louise and Jasper – one of the finest drives in the world – finally heading east to Edmonton. Each leg of this journey (and many like it in western Canada) is covered by GyPSy's commentary, and once I learnt to relax and trust The Voice, I found the experience illuminating.

Admittedly, my entry to Banff that first night was awkward because I had to remember that The Voice wasn't actually God and didn't know which hotel I was going to (I had to stop and ask). But next morning, as soon as I started driving again, it gave me choices. Did I want to go to Lake Louise? Head straight on. Calgary? Take a right. Or why not just mosey around local high spots for a while?

I let it take me to the sweet isolation of local lakes, where I walked a couple of trails. I even took its advice and tried Banff's cable car, in which I soared to the heights of the Rockies for views beyond description.

Afterwards, The Voice asked, would I like to go to Lake Louise now? Turn left on the Trans-Canada Highway… there you go.

So it went. The Icefields Parkway came next. This engrossing, 180-mile wilderness route past hanging glaciers and immense peaks, with occasional roadside sightings of elk and deer, took me steadily north. It was here that The Voice made itself especially useful, urging me to get out of the car from time to time, something easily forgotten on long drives.

So up Johnston Creek I slogged for one sweating hour, past limestone rocks carved by aeons of river-run. Into picnic areas where squirrels bustled. And to the vast snow fields of the Athabasca Glacier, where I walked on glinting ice.

Bedding down in Lake Louise, then Jasper, I explored forests and mountain lakes. But I was always happy to start driving again, as The Voice told me about Alberta's oil riches, or the early settlers who carved this route from wilderness. "I'm going to leave you to enjoy the drive and I'll be back when you reach the turn-off down below," it would say. And it always happened.

I liked it. The operating company has produced 500,000 words of commentary to cover many tourist routes like mine throughout western Canada and is now expanding to Hawaii, mainland America – maybe Europe, too. It's not cheap (up to £26 a day), but the script has been written by journalists and local guides in a tone that sounds conversational rather than tediously literary – it enriched my journey in a way that guidebooks read out of time might not have.

Occasionally it was too cute – "This walk is one of my favourites!" Several times it whisked past well-signed stopping points without saying why. Generally, though, it aimed for a lightly interesting, gently informative style, and pretty much hit the mark.

That was particularly welcome on the 230-mile haul across the Alberta prairie to Edmonton, a journey so greenly uniform it was hard to stay alive, let alone interested. The Voice clearly knew this and threw in desperately distracting stories, some quite cheeky – such as telling me that Albertans "get back to nature" each weekend by splashing mud on their trucks, which made me laugh.

Then Edmonton grew on the horizon like a concrete shrubbery and I had to turn The Voice off at last – a sad moment, though I liked the city. I had a human guide called Cody and he was great. I don't think The Voice will ever put him out of business, because technology can't match human company. But on those drives when you're tempted to slump and dream of mints, The Voice is more than a set of orders – it's a friend.

Canada basics

Nicholas Roe travelled with Timeless Travel (0844 809 4299; timelesstravel.co.uk). Twelve nights in Alberta, taking in Banff, Lake Louise, Jasper and Edmonton, costs from £1,945 per person sharing. This includes car hire with GyPSy, return flight from London and all taxes and accommodation.